Reinforcing the 6MT transmission

SouthArk370Z · 01-19-2020, 08:48 PM

Quote:

Originally Posted by NissanZ34

Is it possible the clutch kit was not properly installed or adjusted and that way it would not fully disengage? But thinking of this, it should not affect the transmission but it should affect more the flywheel and shift shaft?

It doesn't sound like a clutch problem to me, but I'm no expert.

My guess is that less than perfect shifting skills is the main problem. Or it could be you got a bad synchro from the factory. But, given the reputation of the 6MT, I doubt the stoutness of the transmission is the root problem.

Quote:

Originally Posted by NissanZ34

... Would the dealership be able to "rebuild" my current transmission by replacing the synchros with OEM?

I wouldn't trust any dealership to do any out-of-warranty work. And if I can do the in-warranty work myself, I do. YMMV

I haven't rebuilt a manual transmission in quite a while and they were all much older then the 6MT (eg, Ford Toploader) but it's not a difficult job. The FSM (link in my sig) will have exploded diagrams and may have a rebuild procedure.

solidus · 01-19-2020, 09:19 PM

Not for nothing but I make a a couple ugga duggas above 700rwhp and at 150 it was time for me to go to 6th gear. I would have more in it in 5th if I did'nt have Nismo FD but for basically a stock untuned Z to be at 150 in 5th it does'nt seem as if the issue is the tranny. Our tranny is at a point now that other swaps are looking at it as an economy option to hold power without building their own OE tranny.

BGTV8 · 01-20-2020, 01:00 AM

Quote:

Originally Posted by NissanZ34

Hello fellow Z owners. My car has about 50 000km and 4th gear is starting to show wear signs such as being clunky when shifting and not being smooth.

Is there a way to bullet proof the manual transmission? I don't want to buy another OEM transmission that will fail the same way over time.

It's a street car but I'm hard on it. I like speeding and found out my car was speed limited at 240 kmh in 5th gear. Would there be a way to remove the speed limit at low cost? (The dealership is a relative and probably told the mechanic to put the limiter)

Modifications done so far:
I already have a Stage 2 clutch kit with the lightweight flywheel from Zspeed along with their CSC delete kit. GReddy GT Evolution catback exhaust and Fast Intentions HFCs are on the way. Also have a Mishimoto oil cooler kit. K&N drop-in filters with Mishimoto silicone intake tubes.

Sport and Touring package

Thanks

The only way to bullet-proof the transmission is to replace it.

You have 2 obvious choices and some not so obvious.

1. QUAIFE QBE69G with syncro on 6th
2. HOLINGER SG3 if you are not boosted and RD6 if you are

The QBE69G and SG3 will be about the same cost and the RD6 a shed-load more.

Other options is
3. TTI 6-speed sequential from New Zealand

These will not break BUT they are race transmissions and straight cut in lower gears and whine like an entitled millenial who has been separated from his mothers nipple too soon.

These options will cost the equivalent of 4-5 OEM replacement transmissions - apart from the RD6 option which will be USD20K+

Simplest solution is replace the OEM trans

OptionZero · 01-20-2020, 01:30 AM

Street car but hits 150 mph
Transmission failing at 30k miles

Does not sound like a hardware or software problem

phunk · 01-20-2020, 02:44 AM

These transmissions are not worth rebuilding. You toss them out and replace for about $2000.

Changing or removing speed and rev limiters can be done with a tune. Find an UpRev or ECUTEK tuner to tune your car.

2011 Nismo#91 · 01-20-2020, 08:12 AM

I recently replaced my transmission, 2k+labor. Not too bad for a new transmission. Lasted 70k miles and many many miles/hours at the track. I was pushing it pretty hard through the gears when the 5th gear synchro gave out. It's the only weak part of the transmission, you really have to baby it so it won't grind. Even then new one has the same 5th gear issue.

tonythetiger · 01-21-2020, 11:58 AM

Quote:

Originally Posted by phunk

These transmissions are not worth rebuilding. You toss them out and replace for about $2000.

Changing or removing speed and rev limiters can be done with a tune. Find an UpRev or ECUTEK tuner to tune your car.

What is the highest speed and rev limit on these cars, especially NA?

solidus · 01-21-2020, 12:50 PM

Highest speed and rev limit depends on a whole crapload of factors.
Final drive ratio will lower top speed, aero and power. Rev limit will have to figure in upgraded oil pump (which ironically doesn't tolerate much over 8k in oem form. But imho a sensible non race team build wouldn't be looking to go too far past an 8k limit without an Amex Black burning a hole in someone's pocket.

Rusty · 01-21-2020, 12:53 PM

Stock, rev limit is around 7700 rpm. Speed limited to 155 by both ecu and aero.

Zezus · 01-21-2020, 02:21 PM

Quote:

Originally Posted by BGTV8

The only way to bullet-proof the transmission is to replace it.

You have 2 obvious choices and some not so obvious.

1. QUAIFE QBE69G with syncro on 6th
2. HOLINGER SG3 if you are not boosted and RD6 if you are

The QBE69G and SG3 will be about the same cost and the RD6 a shed-load more.

Other options is
3. TTI 6-speed sequential from New Zealand

These will not break BUT they are race transmissions and straight cut in lower gears and whine like an entitled millenial who has been separated from his mothers nipple too soon.

These options will cost the equivalent of 4-5 OEM replacement transmissions - apart from the RD6 option which will be USD20K+

Simplest solution is replace the OEM trans

HEY I'M A MILLENNIAL AND I TAKE OFFENSE TO THIS.
WE AREN'T WHINY AND... Oh.... you've made your point.

01-20-2020, 01:30 AM	#19 (permalink)
OptionZero A True Z Fanatic Join Date: Apr 2011 Location: Sacramento Posts: 3,159 Drives: 15 370Z Nismo 6MT Rep Power: 203226	Street car but hits 150 mph Transmission failing at 30k miles Does not sound like a hardware or software problem SouthArk370Z, Rusty, solidus and 3 others like this. __________________ OptionZero Build Thread

01-20-2020, 02:44 AM	#20 (permalink)
phunk A True Z Fanatic Join Date: Mar 2009 Location: Chicago Posts: 3,654 Drives: 370 Rep Power: 944523	These transmissions are not worth rebuilding. You toss them out and replace for about $2000. Changing or removing speed and rev limiters can be done with a tune. Find an UpRev or ECUTEK tuner to tune your car. Rusty, Spooler and sx moneypit like this. __________________ Charles @ CJ Motorsports : Website \| Facebook \| Instagram \| YouTube Home of the 9 second, stock longblock, stock drivetrain 6MT 370z. 9.91 @ 142mph

01-21-2020, 12:50 PM	#23 (permalink)
solidus Track Member Join Date: Oct 2014 Location: Orlando, Florida Posts: 694 Drives: 15' Nismo Black 6MT Rep Power: 10080	Highest speed and rev limit depends on a whole crapload of factors. Final drive ratio will lower top speed, aero and power. Rev limit will have to figure in upgraded oil pump (which ironically doesn't tolerate much over 8k in oem form. But imho a sensible non race team build wouldn't be looking to go too far past an 8k limit without an Amex Black burning a hole in someone's pocket. Rusty and sx moneypit like this.

01-21-2020, 12:53 PM	#24 (permalink)
Rusty Ronin Samurai - Assassin Join Date: Dec 2011 Location: Fayettenam,Pennsyltucky Age: 68 Posts: 34,851 Drives: 2011 Nismo GM 6M Rep Power: 2684436	Stock, rev limit is around 7700 rpm. Speed limited to 155 by both ecu and aero. elhombre and Zezus like this. __________________ 浪人 - 殺し屋 "The Difficult Anytime, The Impossible By Appointment Only" http://www.the370z.com/members-370z-...o-journal.html

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01-19-2020, 09:19 PM	#17 (permalink)
solidus Track Member Join Date: Oct 2014 Location: Orlando, Florida Posts: 694 Drives: 15' Nismo Black 6MT Rep Power: 10080	Not for nothing but I make a a couple ugga duggas above 700rwhp and at 150 it was time for me to go to 6th gear. I would have more in it in 5th if I did'nt have Nismo FD but for basically a stock untuned Z to be at 150 in 5th it does'nt seem as if the issue is the tranny. Our tranny is at a point now that other swaps are looking at it as an economy option to hold power without building their own OE tranny.

01-20-2020, 08:12 AM	#21 (permalink)
2011 Nismo#91 A True Z Fanatic Join Date: Mar 2011 Location: NJ Posts: 2,379 Drives: slowly Rep Power: 33858	I recently replaced my transmission, 2k+labor. Not too bad for a new transmission. Lasted 70k miles and many many miles/hours at the track. I was pushing it pretty hard through the gears when the 5th gear synchro gave out. It's the only weak part of the transmission, you really have to baby it so it won't grind. Even then new one has the same 5th gear issue.

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